From ancient pagan celebration to anarchist day of rage, we trace the roots of today's historic date

It's the first of May. For most of us, that means an extra day off work is on the horizon and summer is officially about to start. But what are the origins of the holiday, anyway? For many Europeans its roots lie in pagan rituals – but in the modern world, May Day is a date in the calendar for political protest, a historic day for activists worldwide to march and rage against their governments in the fight for better workers' rights.

It all starts with druids. The Gaelic festival, Beltane, was one of four seasonal festivals where they made sacrifices to the god Beli to encourage fertility and protect cattle from disease – basically, a festival to stimulate growth and reproduction. During the Middle Ages, men, women and children would dance gaily around a large pole, usually made from birch wood.

Nobody knows exactly why people started doing this, but the maypole is often cited as an ancient symbol of fertility: it's big, long and – well, you get it. In these ancient, free-spirited and highly sexed times, a procession would take place before the dancing began, led by a woman appointed May Queen for the day. She'd be dressed in green, a symbol of fertility from ye olden days, green being the colour most connected to spring. Towns across Europe still erect a maypole and hold processions.

It's not just medieval Brits that recognised the start of May as a cause for optimism and celebration of sex: civilizations from centuries earlier identified the coming of May as a reason to party. For the ancient Romans, the beginning of May was also an important fertility festival called Floralia – in ancient Egypt, they celebrated Sham El-Nesssim in the hope that women would have strong and healthy babies, and the practice carries on today.

A painting of the Roman goddess Flora, by Renaissance painter Sandro Botticelli

But not all May Day associations are sexual. The first of May also marks International Workers' Day, a celebration of labour and the working classes. The date was chosen by American communists and socialists to commemorate the Haymarket bombings that took place in Chicago in May of 1886. What was intended as a peaceful workers' rights protest descended into murder after a dynamite bomb was hurled at police. The bomb and the retaliatory gunfire that ensued resulted in the deaths of seven police officers and four protestors.

In the aftermath, seven anarchists were sentenced to death without concrete proof that any of them actually threw the bomb that acted as a catalyst for the chaos. International Workers' Day was officially recognised as an annual event in 1891, although had been "unofficially" celebrated in previous years. The day is now recognised as a celebration of the working class as well as labour unions and associations and the rights they achieved (including the eight hour working day).

The anarchist and socialist roots of May Day run deep in countries like Germany. In Berlin, Kreuzberg marks May Day with an annual protest that can be traced back to civil unrest that hit the district on May Day, 1987. On that particular day over twenty years ago, left-wing groups battled police for hours during a street festival and forced them out of the borough. Now, anti–fascist and anarchist groups use the day as an opportunity to gather, demonstrate and confront the police.

It's not just Europe, either – May Day is an international day for people to agitate against those in power. In the weeks after the collapse of the Rana Plaza factory, thousands of Bangladeshi factory workers took to the streets to protest the unfair and unsafe working conditions that killed so many.

Whether you're a paganist, protestor, pilot in distress, or a person just pleased with a day off, May Day and the holiday that comes with it has come to resonate globally – whether that's because fertility is at its optimum, or people want to confront an economic gulf between "the powers" and "the proles".